What did Trump mean when he told Republicans he would be impeached if they lose the midterms?

He meant it fairly literally. Impeachment only requires a simple majority in the House of Representatives. If Democrats win the House in November, they will control the committees, the subpoenas, and the floor schedule, and there is already a queue of issues they would want to investigate, from the conduct of the Iran war to the Epstein files fight with financier Leon Black to the administration's attempts to influence institutions like the Smithsonian.

Trump was impeached twice during his first term, over Ukraine and over January 6, and acquitted both times by a Republican Senate. He knows the mechanics. His warning to House Republicans was a way of saying that their fate and his are tied together, so they should stop hedging.

Would impeachment actually happen? Democratic leaders have been cautious about promising it, because it did not hurt Trump politically the first two times and arguably helped him. The ranking Democrat on the Oversight Committee has outlined priorities that focus more on investigations and legislation than on removal.

But the threat is real enough to shape behaviour. It explains why the White House is pouring money into a handful of races and why the president is personally involved in decisions that would normally be left to party strategists.